A patient simulator was conceived, designed, and fabricated to supplement classroom instruction of critical-care nurses in hemofiltration procedures. Because of the instability of the population that requires renal replacement therapy, a patient- simulation device on which renal-replacement therapies could be performed would permit guided practice opportunities. The simulator consists of a mock circulatory system, complete with venous and arterial reservoirs, venous and arterial lines, and adjustable arterial pressure and venous resistance. The device also includes the hardware necessary to produce clinical alarm states in certain pump-assisted hemofiltration procedures. In addition, the device has proved useful in evaluating the suitability of the support equipment needed to perform renal-replacement therapies in a clinical setting.